The building industry offers numerous different uses for the aforementioned dowels, particular reference being made to the use in steel/concrete composite constructions. For this purpose dowels are welded by a known stud welding process to a steel component to be connected to the concrete. Such a steel component can, for example, be a composite beam (for bridge or building construction), a metal liner for reinforced or prestressed concrete hollow bodies or buildings (DE-A-3 322 998, De-A-30 09 826) or an anchor plate for anchoring loads in a concrete structure. Generally, the concrete is connected directly to the steel component, the latter optionally simultaneously forming the framework or part thereof.
The load-carrying behavior of the dowel is of great constructional significance for such steel/concrete composite components. A distinction must be made between tensile loads, i.e. in the direction of the dowel longitudinal axis, and shear loads, i.e. in the direction of the steel/concrete interface. Great significance is attached to the load-carrying behavior of the dowel with respect to the shear load, which e.g. occurs as a systematic load due to shear stresses between the steel and concrete or can be introduced in the form of a load to be anchored. Shear loading can also occur, for example, as a result of thermal expansions, settlement phenomena, etc.
An important aspect of the dowel load-carrying behavior in the case of shear-off loading is the failure type. The failure of a dowel connection of the aforementioned type can either occur in the form of a steel failure (the dowel shears or tears off) or in the form of a concrete failure (breaking out from a generally funnel-shaped concrete part). It is more favorable for the load-carrying behavior of the connection if a concrete failure can be avoided, such as is also the case with most existing steel/concrete composite constructions by using sufficiently long dowels.
The load-carrying behavior with respect to shear loading is essentially determined by two parameters, namely the failure or breaking load, i.e. the maximum shear force which can be absorbed by the dowel connection, and the failure or break displacement, i.e. the maximum displacement between the steel component and the concrete. The load-carrying behavior can be clearly shown by plotting the shear force over the displacement as a so-called load-strain line. The area under this line is referred to as the working capacity or energy of the dowel and it is desirable for the latter to have a high value.